Manganese complexes phenols

OCjH, Phenol, rhodium complex, 27 292 OC H , Ethanane, 1-phenyl-manganese complex, 26 156-158... 

The SjvAr reaction is another attractive method for diaryl ether synthesis, and reactions of o-nitro- and o-cyanofluorobenzenes with phenols were reported . 7r-Complexation of aryl halides with transition metals activates the aromatic nuclei toward S fAr. Segal employed a ruthenium chlorobenzene complex in the poly(aryl ether) synthesis , and the methodology was extensively studied by Pearson, Rich and their coworkers using manganese complex and later iron and ruthenium complexes in natural product synthesis " . The intramolecular substitution of an aromatic chloride with a phenylalanine derivative takes place at room temperature without racemization (equation 27). 

C 4H gOgP, 1/7-Phospholium, 2,3,4,5-tetra-kis(methoxycarbonyl)-2,2-dimethyl-, manganese complex, 26 167 C,4H2QOgPS. 2W-l,2-Thiaphosphorin-2-ium, 3,4,5,6-tetrakis(methoxycaibonyl)-2,2-dimethyl-, manganese complex 26 165 C,4H720, Phenol, 2,6-di-terr-butyl-, actinide and lanthanide complexes, 27 166 C HjjP, Phosphine, di-rm-butylphenyl-, palladium and platinum complexes, 28 114, 116... 

Depending on the number of coordinated phenolates in the precursor complexes, it has been possible to generate and characterize a (phenoxyl) manga-nese(III) species [Mnm(L BuM<,)(Bu2acac)]2+ or a (phenoxyl)manganese(IV) species [MnIV(LBuMet )]2+. 

Manganese(III) complexes of a number of phenolate pendant arm macrocycles related to the above have also been reported. Thus, both l,4,7-tris(2-hydroxybenzyl)-l,4,7-triazacyclononane and l,4,7-tris(3-t-butyl-2-hydroxybenzyl)-l,4,7-triazacyclononane, on tris-deprotonation, afford monomeric pseudooctahedral complexes with this ion." ... 

The component that undergoes oxidation as photosystem II progresses from one S state to the next is a complex of four atoms of manganese bound to the two central polypeptides of the reaction center. P680t draws electrons from the Mn complex by way of a tyrosine in one of these polypeptides (see fig. 15.17). In the course of this reaction, the phenolic side chain of the tyrosine is oxidized transiently to a free radical. Although the structure of the Mn complex is not yet known, most of the transitions of the complex probably represent sequential oxidations of Mn atoms from the Mn(III) level to Mn(IV). 

First, 1 2 metal complexes of (mainly mono-) azo dyes, without sulfonic or carboxylic acid groups, and trivalent metals (see Section 3.11). The metals are preferably chromium and cobalt nickel, manganese, iron, or aluminum are of lesser importance. Diazo components are mainly chloro- and nitroaminophenols or amino-phenol sulfonamides coupling components are (3-naphthol, resorcinol, and 1-phe-nyl-3-methyl-5-pyrazolone. Formation of a complex from an azo dye and a metal salt generally takes place in the presence of organic solvents, such as alcohols, pyridine, or formamide. An example is C.I. Solvent Red 8, 12715 [33270-70-1] (1). 

Electron transfer from the substrates to 02 proceeds by a redox cycle that consists of copper(II) and copper(I). The high catalytic activity of the copper complex can be explained as follows (1) The redox potential of Cu(I)/Cu(II) fits the redox reaction. (2) The high affinity of Cu(I) to 02 results in rapid reoxidation of the catalyst. (3) Monomers can coordinate to, and dissociate from, the copper complex, and inner-sphere electron transfer proceeds in the intermediate complex. (4) The complex remains stable in the reaction system. It may be possible to investigate other catalysts whose redox potentials can be controlled by the selection of ligands and metal species to conform with these requisites several other suitable catalysts for oxidative polymerization of phenols, such as manganese and iron complexes, are candidates on the basis of their redox potentials. 

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